The present invention relates to additive compositions making it possible to improve the stability and engine performances of the gas oils used as diesel fuel, in particular gas oils of the non-road type.
Since the entry into force of the decree of 10 Dec. 2010, in France the term “gazole non routier” [non-road gas oil] denotes a mixture of hydrocarbons of mineral origin or from synthesis with 7 parts by volume of fatty acid methyl esters according to the minimum requirements of the standard EN 590 or any other standard or specification in force in the EU having a maximum sulphur content of 20 mg/kg at the distribution stage. Previously, domestic fuel oil (dfo) was intended both for heating applications and engine applications; since this Decree, the products are differentiated, i.e. distributed in different distribution networks and required to be stored in separate storage facilities in different networks according to their intended use: stationary applications (heating) on the one hand, and non-stationary applications (non-road gas oil). For heating applications, the fuel oil has a sulphur content of 1,000 pm mass whereas the non-road gas oil has a sulphur content less than or equal to 10 ppm by mass (tolerance 20 ppm); the cetane number of domestic fuel oil is 40 whereas that of non-road gas oil is 51 (better flammability).
In France the use of non-road gas oil, marketed via a specific distribution network and subject to a diferent tax regime to that of motor vehicles is mandatory for                non-road mobile machinery, such as                    construction and civil engineering equipment, in particular bulldozers, all-terrain trucks, excavators, tractors and loaders,            road maintenance equipment            snow ploughs and street sweepers,            self-propelled agricultural vehicles, forestry equipment,            handling equipment, mobile cranes, power lift trucks,            self-propelled ladders and platforms,            ground airport assistance equipment            industrial drilling equipment,            compressors and motor-driven pumps,            railway locomotives,            truck-mounted generators or hydraulic power units,                        agricultural or forestry tractors,        pleasure boats,        inland navigation boats.        
For environmental reasons and/or because of the availability of resources, regulations in many countries encourage the introduction of constantly increasing quantities of products of renewable origin, such as fatty acid esters, into conventional gas oil and non-road gas oil. Thus, at present in the EU, the on-road gas oil used as diesel fuel can contain 7 parts by volume of fatty acid esters, generally fatty acid methyl esters (FAME), essentially or exclusively of vegetable or animal origin (vegetable and/or animal oil esters, in particular vegetable oil methyl esters or VOMEs).
In the past, the machinery engines operating with non-road gas oil were deemed to be unsophisticated and undemanding but the specifications of these engines have developed and are increasingly operating according to technologies as advanced (very high pressure direct injection technologies) as those of on-road motor vehicles. Standard-grade non-road gas oil (currently in compliance with the standard EN 590) sometimes poses problems in terms of:                stability during storage and use: in the case of prolonged storage or in the case of use under conditions of high pressures or temperatures: the antioxidants incorporated in the FAME are not always sufficient to stabilize the product and do not make it possible to combat the action of metals (catalysts of oxidation and degradation phenomena). This instability of the fuel can lead to phenomena of fouling of the filters and injection systems.        extraction of metals: the FAMEs and their by-products have a tendency to promote the extraction of metals with which they are brought into contact, for example transport, storage materials and/or parts or components.        low-temperature performance: in particular for non-road gas oils, given the prolonged period of storage of such fuels which is sometimes greater than 6 months, and taking account of the seasonal nature of the specifications in the winter period or between seasons, the low-temperature performance can be problematic for the user (problems of crystallization, sedimentation, filter plugging etc.).        
There is therefore a need to improve the quality of the gas oils and, in particular, to provide novel additive compositions capable of improving the properties of the gas oils irrespective of their intended use or their composition (with or without products of renewable origin): on-road gas oil or non-road gas oil, of types B0 to B7.
The present invention proposes a high-grade on-road or non-road gas oil which has improved properties compared with the corresponding standard-grade on-road or non-road gas oil (EN 590). Within the meaning of the present invention, several of the properties of the standard gas oil are improved, and in particular the oxidation resistance, storage stability, thermal stability and engine performances (reduction in fouling of the injectors; the following improvements are also possible: reduction in the loss of power; reduction in the tendency of the filters to clog etc.); low-temperature performance (CFPP and pour point). The invention also relates to additive compositions capable of improving the properties of the gas oil, in particular of the non-road gas oil, such as oxidation resistance, storage stability, thermal stability, engine performances (reduction in fouling of the injectors); low-temperature performance (CFPP and pour point), reduction in loss of power, reduction the tendency of the filters to clog etc.) can also be improved. This additive composition added to the fuel (on-road or non-road gas oil) more particularly makes it possible to reduce the tendency of the injectors to be fouled by the fuel. The fouling of the injectors can lead to losses of power but also a degradation of combustion which is responsible for an increase in pollutant emissions.